An Advanced Tape-Stripping Approach for High-Efficiency Sampling on Non-Absorbent Surfaces.

Surface sampling is a frequent task in laboratory work and field studies. Simple methods usually have low efficiency in collecting target substances from surfaces. This study developed an advanced tape-stripping approach for efficient sampling on non-absorbent surfaces. A film-forming solution, prepared using polyvinyl alcohol, is applied to the target surface, where it covers and engulfs the surface deposits and then solidifies into an elastic membrane as it is exposed to air. The deposits are collected by stripping off the membrane and re-dissolving it in water. This new approach exhibited an efficiency of 100% in collecting uniform-size microspheres from glass surfaces and extremely high efficiencies (>96.6%) in detecting selected target DNA materials from glass and stainless steel surfaces. In comparison, the common swab-rinse method exhibited an efficiency of 72.6% under similar measuring conditions. The viability of S. aureus during sampling using the new approach decreased as the ethanol concentration in the applied solution increased. Using a solution with a mass ratio of ethanol of 17.6% balanced the effects of multiplication and degradation of the S. aureus on glass surfaces during sampling. Overall, the proposed approach exhibits high efficiency in collecting living and abiotic matter from non-absorbent surfaces, complementing existing sampling methods.

High attack rate in a Tong Lau house outbreak of COVID-19 with subdivided units in Hong Kong.

Poor housing conditions are known to be associated with infectious diseases such as high Coronavirus disease 2019 (COVID-19) incidences. Transmission causes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in poor housing conditions can be complex. An understanding of the exact mechanism of transmission can help to pinpoint contributing environmental issues. Here, we investigated a Hong Kong COVID-19 outbreak in early 2021 in four traditional Tong Lau houses with subdivided units. There are more than 80 subdivided units of less than 20 m2 floor area each on average. With a total of 34 confirmed COVID-19 cases, the outbreak had an attack rate of 25.4%, being one of the highest attack rates observed in Hong Kong, and ranked among the highest attack rates in reported outbreaks internationally. Tracer gas leakage and decay measurements were performed in the drainage system and in the subdivided units to determine the transport of infectious aerosols by the owner-modified sophisticated wastewater drainage pipe networks and the poor ventilation conditions in some subdivided units. The results show that the outbreak was probably due to multiple transmission routes, i.e. by the drainage pipe spread of stack aerosols, which is enhanced by poor ventilation in the subdivided units.

Aerosol transmission of SARS-CoV-2 due to the chimney effect in two high-rise housing drainage stacks.

Stack aerosols are generated within vertical building drainage stacks during the discharge of wastewater containing feces and exhaled mucus from toilets and washbasins. Fifteen stack aerosol-related outbreaks of coronavirus disease 2019 (COVID-19) in high-rise buildings have been observed in Hong Kong and Guangzhou. Currently, we investigated two such outbreaks of COVID-19 in Hong Kong, identified the probable role of chimney effect-induced airflow in a building drainage system in the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We injected tracer gas (SF6) into the drainage stacks via the water closet of the index case and monitored tracer gas concentrations in the bathrooms and along the facades of infected and non-infected flats and in roof vents. The air temperature, humidity, and pressure in vertical stacks were also monitored. The measured tracer gas distribution agreed with the observed distribution of the infected cases. Phylogenetic analysis of the SARS-CoV-2 genome sequences demonstrated clonal spread from a point source in cases along the same vertical column. The stack air pressure and temperature distributions suggested that stack aerosols can spread to indoors through pipe leaks which provide direct evidence for the long-range aerosol transmission of SARS-CoV-2 through drainage pipes via the chimney effect.

Analysis of efficacy of intervention strategies for COVID-19 transmission: A case study of Hong Kong.

By the end of February 2021, COVID-19 had spread to over 230 countries, with more than 100 million confirmed cases and 2.5 million deaths. To control infection spread with the least disruption to economic and societal activities, it is crucial to implement the various interventions effectively. In this study, we developed an agent-based SEIR model, using real demographic and geographic data from Hong Kong, to analyse the efficiency of various intervention strategies in preventing infection by the SARS-CoV-2 virus. Close contact route including short-range airborne is considered as the main transmission routes for COVID-19 spread. Contact tracing is not that useful if all other interventions have been fully deployed. The number of infected individuals could be halved if people reduced their close contact rate by 25%. For reducing transmission, students should be prioritized for vaccination rather than retired older people and preschool aged children. Home isolation, and taking the nucleic acid test (NAT) as soon as possible after symptom onset, are much more effective interventions than wearing masks in public places. Temperature screening in public places only disrupted the infection spread by a small amount when other interventions have been fully implemented. Our results may be useful for other highly populated cities, when choosing their intervention strategies to prevent outbreaks of COVID-19 and similar diseases.

Most self-touches are with the nondominant hand.

Self-touch may promote the transfer of microorganisms between body parts or surfaces to mucosa. In overt videography of a post-graduate office, students spent 9% of their time touching their own hair, face, neck, and shoulders (HFNS). These data were collected from 274,000 s of surveillance video in a Chinese graduate student office. The non-dominant hand contributed to 66.1% of HFNS-touches. Most importantly, mucous membranes were touched, on average, 34.3 (SE = 2.4) times per hour, which the non-dominant hand contributed to 240% more than the dominant hand. Gender had no significant effect on touch frequency, but a significant effect on duration per touch. The duration per touch on the HFNS was fitted with a log-log linear distribution. Touch behaviour analysis included surface combinations and a probability matrix for sequential touches of 20 sub-surfaces. These findings may partly explain the observed variation in the literature regarding the microbiome community distribution on human skin, supporting the importance of indirect contact transmission route in some respiratory disease transmission and providing data for risk analysis of infection spread and control.

Close contact behavior in indoor environment and transmission of respiratory infection.

Close contact was first identified as the primary route of transmission for most respiratory infections in the early 20th century. In this review, we synthesize the existing understanding of the mechanisms of close contact transmission. We focus on two issues: the mechanism of transmission in close contact, namely the transmission of the expired particles between two people, and the physical parameters of close contact that affect the exposure of particles from one individual to another, or how the nature of close contact plays a role in transmission. We propose the existence of three sub-routes of transmission: short-range airborne, large droplets, and immediate body-surface contact. We also distinguish a "body contact," which is defined with an interpersonal distance of zero, from a close contact. We demonstrate herein that the short-range airborne sub-route may be most common. The timescales over which data should be collected to assess the transmission risk during close contact events are much shorter than those required for the distant airborne or fomite routes. The current paucity of high-resolution data over short distances and timescales makes it very difficult to assess the risk of infection in these circumstances.

Infection Spread and High-Resolution Detection of Close Contact Behaviors.

Knowledge of human behaviors is important for improving indoor-environment design, building-energy efficiency, and productivity, and for studies of infection spread. However, such data are lacking. In this study, we designed a device for detecting and recording, second by second, the 3D indoor positioning and head and body motions of each graduate student in an office. From more than 400 person hours of data. Students spent 92.2%, 4.1%, 2.9%, and 0.8% of their time in their own office cubicles, other office cubicles, aisles, and areas near public facilities, respectively. They spent 9.7% of time in close contact, and each student averagely had 4.0 close contacts/h. Students spent long time on close contact in the office which may lead to high infection risk. The average interpersonal distance during close contact was 0.81 m. When sitting, students preferred small relative face orientation angle. Pairs of standing students preferred a face-to-face orientation during close contact which means this pattern had a lower infection risk via close contact. Probability of close contact decreased exponentially with the increasing distance between two students' cubicles. Data on human behaviour during close contact is helpful for infection risk analysis and infection control and prevention.

Prevalence of the antiphospholipid syndrome and its effect on survival in 679 Chinese patients with systemic lupus erythematosus: a cohort study.

UNLABELLED: In this work we evaluate the prevalence of the antiphospholipid syndrome (APS) and its impact on survival in Chinese patients with systemic lupus erythematosus (SLE). We studied a prospective cohort of southern Chinese patients who fulfilled ≥4 American College of Rheumatology criteria for SLE. The cumulative rate of survival over time was calculated by the Kaplan-Meier method. APS was defined by the 2006 updated consensus criteria. We evaluated the prevalence and manifestations of APS, and compared the survival of patients with and without APS. We followed 679 patients with SLE (92% women; age of onset, 32.5 ± 14 yr) for 9.7 ± 7.3 years. Sixty-eight (10%) patients died and 33 (4.9%) patients were lost to follow-up. Forty-four (6.5%) patients met the criteria for APS, manifested by the following: ischemic stroke (55%), deep venous thrombosis (32%), obstetric morbidity (14%), cardiovascular events (9%), and peripheral vascular disease (9%). Nine (9/44 [20%]) APS patients died, which was more frequent than the non-APS patients (59/635 [9%]; p = 0.02). The cumulative mortality of patients with APS was 4.6% at 5 years, 7.8% at 10 years, and 22.2% at 15 years, which was not significantly higher than that of non-APS patients (5.4% at 5 years, 9.2% at 10 years, and 11.3% at 15 years; p = 0.14). However, if we considered only patients with APS caused by arterial thrombosis, the presence of APS was significantly associated with mortality (hazard ratio, 2.29; 95% confidence interval, 1.13-4.64; p = 0.02). We conclude that the presence of APS increases the mortality risk of Chinese patients with SLE, which is mainly contributed by arterial thrombotic events. CLINICAL SIGNIFICANCE: 1) APS is infrequent in southern Chinese patients with SLE compared to white patients. 2) Arterial thrombosis is a more common manifestation of APS than venous thrombosis in Chinese SLE patients. 3) APS related to arterial thrombosis is associated with increased mortality in Chinese patients with SLE.

Prevalence and risk factors of low bone mineral density in Chinese patients with systemic sclerosis: a case-control study.

OBJECTIVE: To study the prevalence and risk factors of low BMD in patients with SSc. METHODS: Consecutive patients with SSc and an equal number of age- and gender-matched healthy subjects were screened for BMD, fat and lean mass by DXA scan. BMD, body composition and osteoporosis risk factors were compared between patients and controls. Associated factors for low BMD in SSc patients were studied by linear regression. RESULTS: A total of 84 patients with SSc were studied [89% women; age 49.4 (11.3) years; 21% diffuse subtype; disease duration 7.8 (6.4) years]. Except for significantly lower BMI (P = 0.001), fat mass (P = 0.02) and lean body mass (P = 0.006) observed in SSc patients, the prevalence of other osteoporosis risk factors was similar to controls. Fourteen (17%) and five (6%) SSc patients had low BMD expected for age (z-score <-2.0) at the lumbar spine and hip, respectively. BMD of the lumbar spine, hip, femoral neck and whole body was significantly lower in SSc patients than controls, adjusted for age, sex, menopause and BMI (P < 0.05 in all; effect size 0.44-0.54). Linear regression revealed increasing age, menopause and low BMI were independently associated with low BMD at the spine or hip in SSc patients. However, BMD did not correlate with the severity of involvement of the skin and other systems. CONCLUSION: BMD of the spine and hip is significantly lower in patients with SSc than in healthy subjects, which is independent of age, sex, menopause, low BMI and altered body composition.

Prevalence of atherosclerotic risk factors and the metabolic syndrome in patients with chronic inflammatory arthritis.

OBJECTIVE: To evaluate the prevalence of the metabolic syndrome in patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriatic arthritis (PsA). METHODS: Consecutive patients with RA, AS, or PsA who attended our outpatient arthritis clinics between July and November 2009 were recruited for a study of atherosclerotic risk factors and the metabolic syndrome, defined according to the 2009 joint statements using the Asian criteria for central obesity. RESULTS: Nine hundred thirty patients were studied (699 with RA, 122 with AS, and 109 with PsA; 70% women, mean±SD age 51.1±12.7 years). The mean±SD disease duration for patients with RA, AS, and PsA was 5.3±5.4, 6.0±5.6, and 3.6±3.1 years, respectively. The prevalence of metabolic syndrome was significantly higher in PsA (38%) than RA (20%) or AS (11%; P<0.001). The odds ratios (ORs) for the metabolic syndrome compared to age- and sex-matched controls were 0.98 (95% confidence interval [95% CI] 0.78-1.23, P=0.88), 0.59 (95% CI 0.30-1.15, P=0.12), and 2.68 (95% CI 1.60-4.50, P<0.001), respectively, for RA, AS, and PsA. Patients with PsA had a significantly higher prevalence of impaired fasting glucose (30%; P<0.001), low high-density lipoprotein (HDL) cholesterol (33%; P<0.001), high triglycerides level (21%; P=0.008), central obesity (65%; P<0.001), and high blood pressure (56%; P=0.045). In a logistic regression model, the adjusted OR for the metabolic syndrome in PsA was 2.44 (95% CI 1.48-4.01, P<0.001) relative to RA or AS. The adjusted ORs for central obesity, impaired fasting glucose, hypertriglyceridemia, and low HDL cholesterol were also significantly higher in PsA patients. CONCLUSION: Patients with PsA, but not RA or AS, have a significantly higher prevalence of the metabolic syndrome compared to the general population. Among the 3 diseases studied, PsA has the highest prevalence of the metabolic syndrome and is associated with the highest cardiovascular risk.